Spine stabilization system

ABSTRACT

A spinal stabilization system includes a connecting rod, a rod bending device, and a plurality of bone screws. The connecting rod includes an elongate round portion, an elongate head portion and a neck portion connecting the elongate round portion with the elongate head portion. The rod bending device includes an elongate body defining an aperture configured and dimensioned to receive the connecting rod therethrough in a single orientation. The bone screws include a housing portion and a screw shaft distally extending from the housing portion. The housing portion includes an inner housing and an outer housing slidably surrounding at least a portion of the inner housing. The inner housing defines a slot configured and dimensioned to releasably secure the elongate round portion of the connecting rod therein. The outer housing is movable relative to the inner housing between an unlocked state and a locked state.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of International ApplicationNo. PCT/US11/42127, filed on Jun. 28, 2011, and claims priority to, andthe benefit of, U.S. Provisional Patent Application No. 61/359,028,filed on Jun. 28, 2010, and U.S. Provisional Patent Application No.61/537,112, filed on Sep. 21, 2011, the entire contents of each of theseprior applications are hereby incorporated by reference herein.

BACKGROUND

1. Technical Field

The present disclosure relates to orthopedic surgical devices, and moreparticularly, to a spinal stabilization system and a method of usetherefor.

2. Background of Related Art

The spinal column is a complex system of bones and connective tissuesthat provide support for the human body and protection for the spinalcord and nerves. The adult spine is comprised of an upper and lowerportion. The upper portion contains twenty-four discrete bones, whichare subdivided into three areas including seven cervical vertebrae,twelve thoracic vertebrae and five lumbar vertebrae. The lower portionis comprised of the sacral and coccygeal bones. The cylindrical shapedbones, called vertebral bodies, progressively increase in size from theupper portion downwards to the lower portion.

An intervertebral disc along with two posterior facet joints cushion anddampen the various translational and rotational forces exerted upon thespinal column. The intervertebral disc is a spacer located between twovertebral bodies. The facets provide stability to the posterior portionof adjacent vertebrae. The spinal cord is housed in the canal of thevertebral bodies. It is protected posteriorly by the lamina. The laminais a curved surface with three main protrusions. Two transverseprocesses extend laterally from the lamina, while the spinous processextends caudally and posteriorly. The vertebral bodies and lamina areconnected by a bone bridge called the pedicle.

The spine is a flexible structure capable of a large range of motion.There are various disorders, diseases and types of injury, whichrestrict the range of motion of the spine or interfere with importantelements of the nervous system. The problems include, but are notlimited to, scoliosis, kyphosis, excessive lordosis, spondylolisthesis,slipped or ruptured discs, degenerative disc disease, vertebral bodyfracture, and tumors. Persons suffering from any of the above conditionstypically experience extreme or debilitating pain and often timesdiminished nerve function. These conditions and their treatments can befurther complicated if the patient is suffering from osteoporosis, orbone tissue thinning and loss of bone density.

Spinal fixation apparatuses are widely employed in surgical processesfor correcting spinal injuries and diseases. When the disc hasdegenerated to the point of requiring removal, there are a variety ofinterbody implants that are utilized to take the place of the disc.These include interbody spacers, metal cages and cadaver and human boneimplants. In order to facilitate stabilizing the spine and keeping theinterbody in position, other implants are commonly employed, such asbone screws and rods. Depending on the pathology and treatment, asurgeon will select the appropriate spinal rod material and size,specifically, the cross-sectional diameter.

To meet the problem of providing a rigid pedicle screw and rodconstruct, especially for addressing the demands of stiff deformitycorrections, larger rod constructs have been made to improve thestrength of the screw and rod construct. Spinal rods are typically madeof a titanium alloy. However when large deformity corrections need to bemade, these rods are not always strong enough. Larger diameter stainlesssteel rods have been made for these applications, but a larger rodrequires a larger mating screw head to contain the rod which in turnincreases the profile of the construct. In addition, in order to reducethe likelihood of material incompatibility in vivo, the screw assemblyalso needs to be made of stainless steel to match the rod material,which is not a cost effective alternative.

Therefore, a need exists for a cost effective, rigid screw and rodconstruct that can still maintain a low profile, while maintaining thesurgical correction.

SUMMARY

In accordance with an embodiment of the present disclosure, there isprovided a spinal stabilization system including a connecting rod and abone screw. The connecting rod includes an elongate round portion, anelongate head portion and a neck portion connecting the elongate roundportion with the elongate head portion. The bone screw includes ahousing portion and a screw shaft extending distally from the housingportion. The housing portion includes an inner housing and an outerhousing slidably surrounding at least a portion of the inner housing.The inner housing defines a slot configured and dimensioned toreleasably secure the elongate round portion of the connecting rodtherein, wherein the outer housing is movable relative to the innerhousing between an unlocked state in which the elongate round portion ofthe connecting rod is releasable from the slot defined in the innerhousing and a locked state in which the connecting rod is secured in theslot.

The elongate head portion of the connecting rod may have a non-circularcross-section. In particular, the elongate head portion of theconnecting rod may have a substantially rectangular cross-section. Theneck portion of the connecting rod may have an arcuate profile. The neckportion and the elongate head portion of the connecting rod may bedisposed proximal of the inner housing when the elongate round portionof the connecting rod is disposed in the slot defined in the innerhousing. The connecting rod may be monolithically formed. The screwshaft may be fixed relative to the rod receiving portion, or may becoupled with the housing portion to permit uniaxial, monoaxial orpolyaxial motion of the screw relative to the housing portion.

In accordance with another embodiment of the present disclosure, thereis provided a spinal stabilization system including a connecting rod, arod bending device, and a bone screw. The connecting rod includes anelongate round portion, an elongate head portion and a neck portionconnecting the elongate round portion with the elongate head portion.The rod bending device includes an elongate body defining an apertureconfigured and dimensioned to receive therethrough the connecting rod ina single orientation. The bone screw includes a housing portion and ascrew shaft extending distally from the housing portion. The housingportion includes an inner housing and an outer housing slidablysurrounding at least a portion of the inner housing. The inner housingdefines a slot configured and dimensioned to releasably secure theelongate round portion of the connecting rod therein, wherein the outerhousing is movable relative to the inner housing between an unlockedstate in which the elongate round portion of the connecting rod isreleasable from the slot defined in the inner housing and a locked statein which the connecting rod is secured in the slot.

The rod bending device may further include a second aperture configuredand dimensioned to receive the rod oriented orthogonal to the directionin which the first aperture receives the rod. Side walls defining theapertures may have an arcuate profile. The apertures may include arounded portion and a non-circular portion. The non-circular portion ofthe apertures may have a substantially rectangular shape. The rodbending device may further include a third aperture configured anddimensioned to receive the rod oriented oppositely to the orientation inwhich the first aperture receives the rod.

In accordance with another aspect of the present disclosure, there isprovided a method of stabilizing a spine. The method includes providinga spinal stabilization system including a connecting rod, a pair of rodbending devices, and a bone screw. In particular, the connecting rodincludes an elongate round portion, an elongate head portion and a neckportion connecting the elongate round portion with the elongate headportion. The pair of rod bending devices each includes an elongate bodydefining at least one aperture therethrough, each aperture configuredand dimensioned to receive therethrough the connecting rod in a singleorientation. The bone screw includes a housing portion and a screw shaftextending distally from the housing portion. The housing portionincludes an inner housing and an outer housing slidably surrounding atleast a portion of the inner housing. The inner housing defines a slotconfigured and dimensioned to releasably secure the elongate roundportion of the connecting rod therein, wherein the outer housing ismovable relative to the inner housing between an unlocked state in whichthe elongate round portion of the connecting rod is releasable from theslot defined in the inner housing and a locked state in which theconnecting rod is secured in the slot. The method further includesimplanting a plurality of bone screws into a plurality of vertebralbodies, bending the connecting rod using the rod benders, inserting theconnecting rod into the connecting rod slots in the plurality of bonescrews, and locking the connecting rod in the connecting rod slots inthe plurality of bone screws.

Bending the connecting rod may include inserting the connecting rodthrough an aperture in each of the pair of rod bending devices andapplying leveraged force to the connecting rod through the handlemembers of the rod bending devices. Bending the connecting rod mayinclude bending the connecting rod in an anterior-posterior orientation.Bending the connecting rod may include bending the connecting rod in amedial-lateral orientation. Providing multiple apertures in the rodbending devices facilitates bending the rod by permitting the rod to beoriented in various positions relative to the handles.

The pair of rod bending devices may include a plurality of aperturesconfigured and dimensioned to receive therethrough the connecting rod.The plurality of apertures may be defined to receive the rod indifferent orientations. Bending the connecting rod may include insertingthe connecting rod through the apertures of the pair of rod bendingdevices having different orientations and applying twisting force. Inaddition, inserting the connecting rod into the connecting rod slots inthe bone screws may include positioning the elongate round portion ofthe connecting rod in the connecting rod slots in the plurality of bonescrews. Bending the connecting rod may include bending the connectingrod to conform to a desired contour of the spine.

The method may further include orienting the plurality of bone screws tothe contour of the connecting rod prior to locking the connecting rod inthe connecting rod slots in the plurality of bone screws. In addition,locking the connecting rod in the connecting rod slots in the pluralityof bone screws includes partially locking the connecting rod in theconnecting rod slots.

In accordance with another aspect of the present disclosure, there isprovided a kit for spinal surgery. The kit includes a connecting rod, abone screw, a rod reduction device, a partial locker, and a quicklocker. In particular, the connecting rod includes an elongate roundportion, an elongate head portion and a neck portion connecting theelongate round portion with the elongate head portion. The bone screwincludes a housing portion and a screw shaft extending distally from thehousing portion. The housing portion includes an inner housing and anouter housing slidably surrounding at least a portion of the innerhousing. The inner housing defines a slot configured and dimensioned toreleasably secure the elongate round portion of the connecting rodtherein, wherein the outer housing is movable relative to the innerhousing between an unlocked state in which the elongate round portion ofthe connecting rod is releasable from the slot defined in the innerhousing and a locked state in which the connecting rod is secured to theslot. The rod reduction device is configured and adapted for attachmentto the housing portion of the bone screw to reduce the connecting rodinto the slot defined in the inner housing. The partial locker isconfigured to move the outer housing relative to the inner housing topartially lock the connecting rod to the housing. The quick locker isconfigured to move the outer housing with respect to the connecting rodto fully lock the connecting rod to the housing.

In an embodiment, the partial locker may include a distal end portionconfigured and adapted to receive the reduction device while thereduction device remains operably engaged with the bone screw. Inaddition, the kit may further include an unlocker configured and adaptedto move the outer housing of the bone screw relative to the innerhousing and the connecting rod to fully unlock the connecting rod fromthe housing. The kit may also include a rod puller configured andadapted to selectively engage the connecting rod to enable the unseatingof the connecting rod from within the slot of the inner housing of thebone screw.

In accordance with still another aspect of the present disclosure, thereis provided a method of stabilizing a spine. The method includesproviding a spinal stabilization system including a connecting rod, abone screw, a rod reduction device, a partial locker, and a quicklocker. In particular, the connecting rod includes an elongate roundportion, an elongate head portion and a neck portion connecting theelongate round portion with the elongate head portion. The bone screwincludes a housing portion and a screw shaft extending distally from thehousing portion. The housing portion includes an inner housing and anouter housing slidably surrounding at least a portion of the innerhousing. The inner housing defines a slot configured and dimensioned toreleasably secure the elongate round portion of the connecting rodtherein. The outer housing is movable relative to the inner housingbetween an unlocked state in which the elongate round portion of theconnecting rod is releasable from the slot defined in the inner housingand a locked state in which the connecting rod is secured to the slot.The rod reduction device is configured and adapted for attachment to thehousing portion of the bone screw to reduce the connecting rod into theslot defined in the inner housing. The partial locker is configured tomove the outer housing relative to the inner housing to partially lockthe connecting rod to the housing. The quick locker is configured tomove the outer housing with respect to the connecting rod to fully lockthe connecting rod to the housing. The method further includesimplanting a plurality of bone screws into a plurality of vertebralbodies, inserting the elongated round portion of the connecting rod intothe slots in the plurality of bone screws with the rod reduction deviceand locking the connecting rod in the slots in the plurality of bonescrews.

In an embodiment, locking the connecting rod in the slots in theplurality of bone screws may include partially locking the connectingrod in the slots with the partial locker. In addition, locking theconnecting rod in the slots in the plurality of bone screws may includefully locking the connecting rod in the slots with the quick locker.

In accordance with still yet another embodiment of the presentdisclosure, there is provided a spinal stabilization system including apair of connecting rods and a cross connector assembly configured tocouple the pair of connecting rods. Each connecting rod includes anelongate round portion, an elongate head portion and a neck portionconnecting the elongate round portion with the elongate head portion.The cross connector assembly includes a pair of connectors each defininga recessed portion configured to secure one of the pair of connectingrods therein and an intermediate portion connecting the pair ofconnectors, wherein the recessed portion includes an arcuate wallconfigured to receive the elongate round portion of the connecting rodand an opposing non-circular wall configured to receive the elongatehead portion of the connecting rod.

In an embodiment, each connector may define a slit configured to flex orenlarge the dimensions of the recessed portion to facilitate insertionof the connecting rod. The non-circular wall may have a substantiallyrectangular cross-section. The recessed portion may include a pair ofopposing fingers to secure the connecting rod within the recessedportion. Furthermore, the intermediate portion may be retractable toenable adjustment of a length of the intermediate portion.

In another embodiment, the spinal stabilization system may furtherinclude a circular rod, wherein the arcuate wall of the recessed portionis configured to receive the circular rod therein.

In accordance with still yet another embodiment of the presentdisclosure, there is provided a spinal stabilization system including apair of connecting rods and a cross-connector assembly configured tocouple the pair of connecting rods. Each connecting rod includes anelongate round portion, an elongate head portion and a neck portionconnecting the elongate round portion with the elongate head portion.The cross connector includes a pair of connectors each defining arecessed portion configured to secure one of the pair of connecting rodstherein. The recessed portion is configured to receive the elongate headportion of the connecting rod. Each recessed portion defines a pair offingers to secure the elongate head portion therebetween.

In an embodiment, the cross connector may be made of a relativelyflexible material to provide a snap fit engagement with the elongatehead portion.

In accordance with still yet another embodiment of the presentdisclosure, there is provided a spinal stabilization system including aconnecting rod and a bone screw. The connecting rod includes a firstportion and a second portion. The first portion includes an elongateround portion, an elongate head portion, and a neck portion connectingthe elongate round portion with the elongate head portion. The secondportion includes a circular rod. The circular rod is coupled to theelongate round portion. The bone screw includes a housing portion and ascrew shaft extending distally from the housing portion. The housingportion includes an inner housing and an outer housing slidablysurrounding at least a portion of the inner housing. The inner housingdefines a slot configured and dimensioned to releasably secure theconnecting rod therein, wherein the outer housing is movable relative tothe inner housing between an unlocked state in which the connecting rodis releasable from the slot defined in the inner housing and a lockedstate in which connecting rod is secured to the slot.

In an embodiment, the connecting rod may further include a transitionportion connecting the first and second portions. The transition portionmay be longitudinally tapered. In particular, the transition portion mayinclude a first end having a cross section substantially identical to across section of the first portion and a second end having a crosssection substantially identical to the cross section of the secondportion. In addition, the first end may be adjacent the first portionand the second end may be adjacent the second portion. In anotherembodiment, the connecting rod may be monolithically formed.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present disclosure will becomeapparent to one skilled in the art to which the present disclosurerelates upon consideration of the following description of thedisclosure with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of a spinal stabilization system inaccordance with an embodiment of the present disclosure;

FIG. 2 is an end view of the spinal stabilization system of FIG. 1;

FIG. 3 is a top view of the spinal stabilization system of FIG. 1;

FIG. 4 is a side view of the spinal stabilization system of FIG. 1;

FIG. 5 is a partial cross-sectional view of a taper lock screw of thespinal stabilization system of FIG. 1 shown in an unlocked position toreceive a rod;

FIG. 5A is an end, cross-sectional view of the spinal stabilizationsystem of FIG. 1 in a locked position;

FIG. 6 is a perspective view of a connecting rod of the spinalstabilization system of FIG. 1;

FIG. 7 is an end view of the connecting rod of FIG. 6;

FIG. 8 is a top view of the connecting rod of FIG. 6;

FIG. 9 is a side view of the connecting rod of FIG. 6;

FIG. 10 is a graph illustrating deflection of the connecting rod of FIG.6;

FIG. 11 is a graph illustrating flexural rigidity of the connecting rodof FIG. 6;

FIG. 12A is a side view of a rod bender device for use with the spinalstabilization system of FIG. 1;

FIG. 12B is a side cross-sectional view of the area of detail indicatedin FIG. 12A;

FIG. 13 is a perspective view of a pair of rod bender devices of FIG.12A having the connecting rod of FIG. 6 inserted therethrough;

FIG. 14 is a perspective view of the pair of rod bender devices of FIG.13 having the connecting rod of FIG. 6 inserted therethrough in adifferent orientation;

FIG. 15 is a perspective view of a spinal correction procedure on adeformed spine utilizing the spine stabilization system of FIG. 1;

FIGS. 16A and 16B are flow charts illustrating an overview of a methodof stabilizing a spine;

FIG. 17 is a perspective view of a rod reduction device for use with thespinal stabilization system of FIG. 1;

FIG. 17A is a front, cross-sectional view of the rod reduction device ofFIG. 17 operatively connected to a screw and a connecting rod;

FIG. 18 is a perspective view of a partial locker for use with thespinal stabilization system of FIG. 1;

FIG. 18A is a longitudinal cross-sectional view of the partial locker ofFIG. 18 operatively connected to a screw and a connecting rod;

FIG. 18B is a longitudinal cross-sectional view of the area of detailindicated in FIG. 18A;

FIG. 19 is a perspective view of a quick locker for use with the spinalstabilization system of FIG. 1;

FIG. 19A is a longitudinal cross-sectional view of the quick locker ofFIG. 19 operatively connected to a screw and a connecting rod;

FIG. 19B is a longitudinal cross-sectional view of the area of detailindicated in FIG. 19A operatively connected to a screw and a connectingrod;

FIG. 20 is a perspective view of an unlocker for use with the spinalstabilization system of FIG. 1;

FIG. 20A is a partial, longitudinal cross-sectional view of the unlockerof FIG. 20;

FIG. 21 is a perspective view of a rod puller for use with the spinalstabilization system of FIG. 1;

FIG. 21A is a partial, side view of the rod puller of FIG. 21operatively connected to a screw and a connecting rod;

FIGS. 22-24 are perspective views of various rod benders for use withthe spinal stabilization system of FIG. 1;

FIG. 25 is a perspective view of a cross connector assembly for use withthe spinal stabilization system of FIG. 1;

FIG. 26 is a top view of the cross connector assembly of FIG. 25;

FIG. 27 is a side view of the cross connector assembly of FIG. 25;

FIG. 28 is an end view of the cross connector assembly of FIG. 25;

FIG. 29 is an exploded perspective view of the cross connector assemblyof FIG. 25 with parts separated;

FIG. 30 is an end, cross-sectional view of the cross connector assemblyof FIG. 25;

FIG. 31 is an end view of the cross connector assembly of FIG. 25;

FIGS. 32 and 33 are perspective views of other cross connectorassemblies for use with the spinal stabilization system of FIG. 1;

FIG. 34 is a perspective view of an axial connector illustrating usewith different connecting rods;

FIG. 34A is a side view of the axial connector of FIG. 34 operativelycoupling different connecting rods;

FIG. 35 is a perspective view of the axial connector of FIG. 34illustrating use with the connecting rods of FIG. 1;

FIG. 36 is a perspective view of an offset connector illustrating usewith different connecting rods;

FIG. 36A is a side view of the offset connector of FIG. 36 operativelycoupling different connecting rods;

FIG. 37 is a perspective view of the offset connector of FIG. 36illustrating use with the connecting rods of FIG. 1;

FIG. 37A is a side view of the offset connector of FIG. 37 operativelycoupling the connecting rods of FIG. 1;

FIG. 38 is a perspective view of a spinal hook for use with the spinalstabilization system of FIG. 1;

FIG. 38A is a side view of the spinal hook of FIG. 38 operativelycoupled with the connecting rod of FIG. 7;

FIG. 39 is a perspective view of a spinal stabilization system inaccordance with yet another embodiment of the present disclosure; and

FIG. 40 is an end view of the spinal stabilization system of FIG. 39.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will now be described in detailwith reference to the drawings, in which like reference numeralsdesignate identical or corresponding elements in each of the severalviews. As used herein, the term “distal,” as is conventional, will referto that portion of the instrument, apparatus, device or componentthereof which is farther from the user while, the term “proximal,” willrefer to that portion of the instrument, apparatus, device or componentthereof which is closer to the user. In addition, the term “cephalad” isused in this application to indicate a direction toward a patient'shead, while the term “caudad” indicates a direction toward the patient'sfeet. Further still, for the purposes of this application, the term“medial” indicates a direction toward the middle of the body of thepatient, while the term “lateral” indicates a direction toward a side ofthe body of the patient, i.e., away from the middle of the body of thepatient. The term “posterior” indicates a direction toward the patient'sback, while the term “anterior” indicates a direction toward thepatient's front. In the following description, well-known functions orconstructions are not described in detail to avoid obscuring the presentdisclosure in unnecessary detail.

With reference to FIGS. 1-4, an embodiment of the present disclosure isshown generally as a spinal stabilization system 100. Spinalstabilization system 100 includes at least one bone screw 50 and aconnecting rod 10 releasably secured to bone screw 50. Bone screw 50 isa multi-planar taper lock screw that enables manipulation of a screwshaft 52 about multiple axes, whereby bone screw 50 is capable ofsecuring connecting rod 10 with bone screws 50 on multiple vertebralbodies that are aligned in the spinal column on different planes due tothe natural curvature of the spine. However, it is also envisioned thatbone screws 50 may be, for example, fixed angle screw, uniplanar screwsor monoaxial taper lock screws.

One suitable taper lock screw is commercially available from K2M, Inc.(Leesburg, Va.) under the trade name MESA™. In addition, suitablemulti-planar taper lock screws are shown and described in U.S. PatentApplication Publication 2008/0027432 and in U.S. Patent ApplicationPublication 2007/0093817, both of which are herein incorporated byreference in their entireties. It is contemplated that other types ofscrews such as, e.g., a fixed screw in which the head of the screw hasno movement relative to the screw shaft, a mono-axial screw such as thatdisclosed in U.S. Patent Application Publication 2009/0105716, and auni-axial screw such as that disclosed in U.S. Patent ApplicationPublication 2009/0105769 may be utilized. Suitable mono-axial anduni-axial screws are also commercially available under the trade nameMESA™.

With reference now to FIGS. 4, 5 and 5A, a suitable multi-planar taperlock bone screw 50 includes a dual layered housing 60 and screw shaft 52having a spherically configured screw head 54 rotatably coupled withhousing 60. In particular, dual layered housing 60 includes an outerhousing 62 and an inner housing 64. Outer housing 62 can be selectivelypositioned relative to inner housing 64 to fully lock screw head 54 andconnecting rod 10 in position within inner housing 64 (see FIG. 4) oralternatively to selectively partially lock screw head 54 and/orconnecting rod 10 in position while permitting a sliding and/or rotatingmotion of the connecting rod 10 relative to screw head 54, and the screwhead 54 relative to bone screw 50, respectively. Specifically, outerhousing 62 is configured such that at least a portion of an innersurface of outer housing 62 is capable of sliding over a portion of anouter surface of inner housing 64 in upward and downward directionsalong the longitudinal axis of bone screw 50. When outer housing 62 isslid upward in relation to inner housing 64 an inner surface of outerhousing 62 causes inner housing 64 to impart compressive force radiallyinward to secure connecting rod 10 at least partially disposed therein.

With continued reference to FIG. 5, inner housing 64 defines aconnecting rod slot 70 that is configured and dimensioned to accommodatethe connecting rod geometry contemplated by the present disclosure, andto retain connecting rod 10 in inner housing 64 without impairing thelocking ability of bone screw 50. Specifically, an elongate roundedsection 12 of connecting rod 10 is releasably secured in connecting rodslot 70 of inner housing 64, as will be discussed in detail below. Theterm “rounded” in elongate rounded section 12 refers to a portion ofconnecting rod 10 having a generally circular/arcuate cross-section thatis received in bone screw 50. In particular, inner walls that defineconnecting rod slot 70 imparts compressive force to connecting rod 10disposed in connecting rod slot 70, whereby the inner walls serve tosecurely lock and hold connecting rod 10 in its relative position toinner housing 64. This required forced is provided by the operationalengagement of a locking device (not shown) with bone screw 50 thatresults in an upward sliding motion of outer housing 62 relative toinner housing 64.

Inner housing 64 further defines a screw head articulation recess 66 ina lower portion of inner housing 64. The interior surface of screw headarticulation recess 66 has a complementary surface configuration to thegenerally spherical shape of screw head 54 to facilitate multi-planarrotational articulation of screw head 54 within articulation recess 66.The lower-most portion of inner housing 64 defines a screw shaft exitportal 68 that is sized small enough to retain the spherical screw head54 within screw head articulation recess 66, but that is large enough toallow multi-directional movement of screw shaft 52 that extends exteriorto inner housing 64.

Outer housing 62 includes a receiving element configured to facilitategrasping of bone screw 50 by a locking and/or unlocking instrument (notshown) that can insert and lock connecting rod 10 securely into place inbone screw 50 or selectively unlock connecting rod 10 from bone screw 50using complementarily designed unlocking instruments. The receivingelement is a proximally located annular flange 74 radially extendingfrom the upper portion of the outer surface of outer housing 62.

With reference back to FIGS. 1-4, connecting rod 10 is configured anddimensioned to be selectively and releasably secured to bone screw 50.Connecting rod 10 is defined by an elongate body of a particular length.The elongate body is made of a biocompatible material such as Titanium(Ti-CP) and its alloys (e.g., Ti-6A1-4V), Cobalt-Chrome Alloy (CoCr) orStainless Steel (SS).

With reference to FIGS. 6 and 7, the elongate body of connecting rod 10includes an elongate rounded section 12 having a substantially circularcross-section (see FIG. 7), an elongate head portion 14, and a neckportion 16 that connects and transitions elongate rounded section 12into elongate head portion 14, thereby providing reduced stressconcentration along the elongate body of connecting rod 10. Neck portion16 has dimensions that are smaller than those of elongate roundedsection 12 and elongate head portion 14. The neck portion may define apair of concave sides joining the elongate head portion to the elongaterounded portion, so that the concave sides provide clearance for thetaper lock screw housings. The elongate body of connecting rod 10 may bemonolithically formed as a unitary construct. For example, connectingrod 10 may be machined from a single piece of bar stock.

With reference now to FIGS. 6 to 9, elongate head portion 14 may have anon-circular cross-section. As shown, elongate head portion 14 has asubstantially rectangular cross-section having suitable dimensions of,for example, about 6 mm×about 1 mm (0.246 in.×0.039 in.). However, it isenvisioned that elongate head portion 14 may have a cross-section thatis substantially square, elliptical or any other shape to add rigidityto round section 12 of connecting rod 10.

With particular reference back to FIGS. 5 and 6, elongate roundedsection 12 of connecting rod 10 is configured and dimensioned to bereceived in connecting rod slot 70 of inner housing 64 (see FIG. 2). Forexample, round section 12 of connecting rod 10 may have a standarddiameter of, for example, about 5.5 mm, suitable to mate with connectingrod slot 70. Bone screw 50 may be positioned at any desired point alongthe elongate body of connecting rod 10. When connecting rod 10 issecured to bone screw 50, neck portion 16 of connecting rod 10 isdisposed at the top of bone screw 50 (FIG. 2) and does not interferewith the interaction between connecting rod 10 and bone screw 50.Furthermore, elongate head portion 14 of connecting rod 10 is disposedabove the top of taper lock screw 50. While elongate head portion 14 isdisposed above elongate rounded section 12, head portion 14 does notappreciably increase the height profile of the screw-rod combination.

Connecting rod 10 affords greater strength and rigidity in comparisonwith ordinary circular rods with comparable dimensions. With referencenow to FIG. 10, connecting rods 10 made of different materials wereplaced under cantilever loading and were analyzed under Finite ElementAnalysis (FEA), wherein each rod sample was 100 mm in length. The distalend was fixed while the proximal end was subject to 200 N of force.Connecting rod 10 lacks radial symmetry. Accordingly, the graphdifferentiates deflection of connecting rod 10 between cantileverloading in flexion/extension and lateral bending.

For example, placing a circular rod formed from a titanium alloy (e.g.Ti-6A1-4V) under the same loading conditions as connecting rod 10 inFIG. 10 results in a deflection of about 13.4 mm for a rod diameter of5.5 mm and a deflection of about 5.00 mm for a rod with a diameter of7.00 mm. A stainless steel rod placed under the same loading conditionsresults in a deflection of about 8.00 mm for a rod diameter of 5.5 mmand a deflection of about 3.00 mm for a rod diameter of 7.00 mm. A rodformed from a cobalt chrome alloy under the same loading conditions hasa deflection of about 6.8 mm for a rod diameter of 5.5 mm and adeflection of about 2.8 mm for a rod diameter of 7.00 mm.

Flexural rigidity of connecting rod 10 is shown in FIG. 11. For example,circular rods made of a titanium alloy (e.g. Ti-6A1-4V) placed under thesame loading conditions as connecting rod 10 in FIG. 11 have flexuralrigidity of about 5.01 N-m² for a rod diameter of 5.5 mm and 23.5 N-m²for a rod diameter of 8.00 mm. Circular rods made of stainless steelplaced under the same loading conditions have flexural rigidity of about9.0 N-m² for a diameter of 5.5 mm and 40.01 N-m² for a rod diameter of8.00 mm. Circular rods made of cobalt chrome alloy placed under the sameloading conditions have flexural rigidity of about 10.1 N-m² for a roddiameter of 5.5 mm and 47.0 N-m² for a rod diameter of 8.00 mm.

Connecting rod 10 provides a greater stiffness and rigidity thancircular rods having comparable dimensions in various materials. Assuch, connecting rod 10 and bone screw 50 construct affords greaterrigidity and strength without increased bulk and profile. In addition,such construct, as shown, does not require any design changes to taperlock screw 50, and thus advantageously provides efficiency ofmanufacture and inventory.

With reference now to FIGS. 12 to 14, spinal stabilization system 100may further include rod bender devices 80. Each rod bender devices 80define matching apertures 88 configured to receive and hold at least aportion of connecting rod 10 therein. Rod bender device 80 includes ahandle member 82, an elongate body 84 extending distally from handleportion 82, and an engaging portion 86 coupled to elongate body 84.Elongate body 84 is coupled or formed with handle member 82 and engagingportion 86 so as to reduce stress concentration. Handle member 82 maycontain scalloped sections to facilitate gripping by the user. Elongatebody 84 may have a rectangular cross-section and may define a cavityalong the length thereof to reduce the weight of device. Engagingportion 86 defines at least one aperture 88 adapted and dimensioned toreceive therethrough connecting rod 10. In particular, inner walls thatdefine aperture 88 are configured to permit insertion of connecting rod10 through aperture 88 in a single orientation with respect to suchaperture.

Aperture 88 has an arcuate end wall 88 a configured to engage elongaterounded section 12 of connecting rod 10, an opposite substantiallystraight end wall 88 b configured to engage the substantially flatportion of elongate head portion 14 of connecting rod 10, and connectingside walls 88 c connecting arcuate end wall 88 a and the substantiallystraight end wall 88 b. In this manner, connecting rod 10 is insertedinto each aperture 88 in a single orientation. Thus, in order toaccommodate insertion of connecting rod in aperture 88 in variousorientations, a plurality of apertures 88 is defined in engaging portion86 in different orientations, as shown in FIG. 12A-12B. For example, thepair of apertures 88 defined in engaging portion 86 is oriented at a90-degree angle, whereby the rectangular portions of apertures 88 aresubstantially orthogonal to each other. In this manner, the user canbend connecting rod 10 in both an anterior-posterior orientation and amedial-lateral orientation. It is also contemplated that connecting rod10 may be inserted in non-corresponding apertures 88 in rod benderdevices 80 to facilitate twisting of connecting rod 10, if necessary ordesired.

The length of elongate body 84 is, for example, 18 inches. However, thelength of elongate body 84 may be tailored to meet the needs of thesurgical application to provide a suitable long moment arm necessary toprovide the user a mechanical advantage to bend connecting rod 10. Inaddition, it is also envisioned that elongate body 84 may be a hollowtubular member and/or define lightening holes to reduce the weight ofdevice 80.

With reference now to FIGS. 16A and 16B, a method of performing spinalstabilization utilizing spinal stabilization system 100 is illustrated.Initially, the user implants a plurality of bone screws 50 in vertebralbodies of a patient in step 500. Preliminary to the operation of bonescrew 50, outer housing 62 is positioned in the open/unlocked position,that is, outer housing 62 is moved downward relative to inner housing64. Screw shaft 52 can then be driven into the desired vertebral body byproviding torsional force via a driving tool (not shown) configured tomate with and grip bone screw 50. After screw shaft 52 is positionedwithin the vertebral body and the driving tool removed from the screw,elongate rounded section 12 of connecting rod 10 can be positionedtransversely within connecting rod slot 70 defined in inner housing 64.

However, prior to securing connecting rod 10 with bone screw 50, thesurgeon can manipulate and correct the curve of the spinal column, i.e.,to manually manipulate and reduce the “rib hump” in step 502. Afterplacing the spine in proper position in step 504, the surgeon can bendconnecting rod 10 in step 506 prior to securing connecting rod 10 to thefirst two points of the spinal column where the construct is to beattached.

The surgeon can bend connecting rod 10 by utilizing the pair of rodbender devices 80 in step 508. In use, connecting rod 10 is insertedthrough selected apertures 88 of rod bender devices 80 and force isapplied at handle members 82 of rod bender devices 80 to appropriatelycontour and shape connecting rod 10 to a desired curve in step 514.

In particular, spinal stabilization system 10 can be utilized to correctspinal deformity (see FIG. 15) in step 510 to appropriately contour andshape connecting rod 10 to a desired curvature of the spine, e.g., thesagittal curve, in step 512.

For example, a rod reduction device or plurality of rod reductiondevices 150 including a screw jack mechanism and a manipulation deviceor plurality of manipulation devices 170 adapted and configured forattachment to heads of taper lock bone screws 50, and which providesleverage (i.e., long moment arm) to facilitate the manipulation of thespine may be utilized to orient the spine and place connecting rod 10 inbone screw 50. In particular, rod reduction device 150 includes ahousing with two arms that are pivotally attached to the housing, ananvil movably mounted on the two arms, and a screw threadably coupledwith the housing and the anvil. The distal ends of arms provide positiveand secure attachment of rod reduction device 150 with bone screw 50.When the anvil is adjacent the housing the two arms are pivotedoutwards, such that the distal ends of the arms can receive bone screw50 therebetween. Rotating the screw of rod reduction device 150 in afirst direction advances the screw through the housing and causescorresponding movement of the anvil toward bone screw 50, which in turncauses the arms to move toward each other and provides positiveengagement with bone screw 50. The anvil defines an arcuately definedrecess that is configured and dimensioned for positively engagingconnecting rod 10. The recess cooperates with connecting rod slot 70 anddefines an opening adapted for receiving connecting rod 10. Withconnecting rod 10 positioned in or near connecting rod slot 70, thesurgeon continues to advance the screw capturing connecting rod 10between the recess of the anvil and connecting rod slot 70. When theanvil is sufficiently advanced, the recess presses upon the outersurface of connecting rod 10 and pushes it into connecting rod slot 70.A suitable rod reduction device 150 is disclosed in a commonly assignedU.S. Patent Application Publication No. 2009/0018593, the completedisclosure of which is fully incorporated herein by reference.

With reference to FIG. 15, rod reduction device 150 is attached to theheads of bone screws 50 on the concave side of the spinal deformity.Manipulation device 170 is placed on bone screws 50 on the convex sideof the spinal deformity. Depending on the nature of the deformity,however, rod reduction device 150 may be used on both sides of thedeformity.

At this time, connecting rod 10 is positioned in slots 70 of bone screws50 implanted in vertebral bodies in step 516. With screw shaft 52 andscrew head 54 being fixed in position relative to the vertebral body,bone screws 50 may be partially locked in step 518. In particular, innerhousing 64 and the circumferentially disposed outer housing 62 can bearticulated relative to screw head 54 as necessary to manipulate thedisposition of connecting rod 10 within bone screw 50 to make necessaryadjustments in step 520. For example, bone screw 50 may be partiallylocked to connecting rod 10 for compression, distraction and rotationwithout torsional stress being applied to the spine.

Upon completion of the necessary positional adjustments of inner housingrecess 66 relative to screw head 54 and the adjustments of connectingrod 10 relative to connecting rod slot 70, outer housing 62 can begrasped by the operator using the complementarily configured lockingdevice. Activation of the locking device slides the outer housing upwardcircumferentially over the outer surface of inner housing 64 while thepush rod holds down connecting rod 10 and inner housing 64 so that bonescrew 50 is reconfigured from the open or unlocked position to closed orlocked position in step 522. Similarly, the operator can use thecomplementarily configured unlocking device to grasp inner housing 64and slidably move outer housing 62 downward along the outer surface ofinner housing 64 from a closed or locked position to an open or unlockedposition. The rod and bone screw combination of the present disclosuremay provide particular advantages in scoliosis or other spinal deformitysurgery in which high stress levels are exerted upon such constructs atparticular levels in the construct or over the entire length of such aconstruct.

With reference to FIGS. 17 and 17A, spinal stabilization system 100 mayfurther include a rod reduction device 200 configured and adapted forattachment to housing 60 of taper lock bone screws 50. In particular,rod reduction device 200 includes a housing 220 with two arms 222 thatare pivotally attached to housing 220, an anvil 230 movably mounted ontwo arms 222, and a screw 240 threadably coupled with housing 220 andanvil 230. In particular, each arm 222 pivots about a pivot pin 225disposed in housing 220, whereby each arm 222 pivots relative to housing220. Distal ends 224 of arms 222 provide positive and secure attachmentof rod reduction device 200 with bone screw 50. When anvil 230 isadjacent housing 220, two arms 222 are pivoted outwards, such thatdistal ends 224 of arms 222 can receive bone screw 50 therebetween.Screw 240 may be rotated using a tool (not shown) that engages a recess233 in screw 240. Rotating screw 240 of rod reduction device 200 in afirst direction advances screw 240 through housing 220 and causescorresponding movement of anvil 230 toward bone screw 50, which in turncauses arms 222 to move toward each other and provides positiveengagement with bone screw 50.

Anvil 230 has an arcuately defined recess 232 that is configured anddimensioned for positively engaging connecting rod 10. The arcuate shapeof recess 232 accommodates, i.e., drives, connecting rod 10 into bonescrew 50, independent of the orientation of connecting rod 10. Recess232 cooperates with connecting rod slot 70 and defines an openingadapted for receiving connecting rod 10. With connecting rod 10positioned in or near connecting rod slot 70, the surgeon continues toadvance screw 240 capturing connecting rod 10 between recess 232 ofanvil 230 and connecting rod slot 70. When anvil 230 is sufficientlyadvanced, recess 232 presses upon the outer surface of connecting rod 10and urges it into connecting rod slot 70.

With reference to FIGS. 18-18B, spinal stabilization system 100 may alsoinclude a partial locker 300. Partial locker 300 includes a distal endportion 310 configured to be received about reduction device 200 whilereduction device 200 remains operably engaged with inner housing 64 ofbone screw 50. In particular, distal end portion 310 of partial locker300 includes a plurality of graspers 322 configured to engage outerhousing 62 of bone screw 50. In particular, the plurality of graspers322 are coupled operatively with a handle member 350. When handle member350 is in an unactuated position, as shown in FIG. 18, the plurality ofgraspers 322 extend radially outward, and when handle member 350 is inan actuated position, as shown in FIGS. 18A and 18B, the plurality ofgraspers 322 move radially inward to engage outer housing 62 and to moveouter housing 62 relative to inner housing 64 to partially lockconnecting rod 10 to dual layered housing 60. A suitable partial lockeris disclosed in commonly assigned U.S. Patent Application PublicationNos. 2009-0018593 and 2007-0093817, the complete disclosures of whichare fully incorporated herein by reference.

With reference now to FIGS. 19-19B, spinal stabilization system 100 mayfurther include a quick locker 500 including a distal end portion 510that is configured to operably engage outer housing 62 of bone screw 50and connecting rod 10. In particular, quick locker 500 is used afterreduction device 200 has been disengaged from dual layered housing 60 ofbone screw 50. Distal end portion 510 is configured to move outerhousing 62 with respect to connecting rod 10 to fully lock connectingrod 10 to dual layered housing 60. Optionally, connecting rod 10 may bepartially locked with dual layered housing 60.

With reference now to FIGS. 20-21A, an unlocker 600 and a rod puller 700may also be provided as part of spinal stabilization system 100.Unlocker 600 includes a distal end portion 610 having a pair of armmembers 622 coupled operatively to a lever 650. Each arm member 622includes a grasper 622 a. The pair of graspers 622 a are configured andadapted to engage outer housing 62 of bone screw 50 to move outerhousing 62 relative to inner housing 64 and connecting rod 10 to fullyunlock connecting rod 10 from dual layered housing 60. In particular,when lever 650 is squeezed against an elongate body 630, graspers 622 amove outer housing 62 distally relative to inner housing 64 andconnecting rod 10 to fully unlock connecting rod 10 from dual layeredhousing 60. Upon fully unlocking connecting rod 10 from dual layeredhousing 60, rod puller 700 may be utilized to remove connecting rod 10from connecting rod slot 70 of inner housing 64 of bone screw 50. Rodpuller 700 includes a distal end portion 710 having a pair of spacedapart hook portions 722 configured and adapted to engage connecting rod10. In particular, hook portion 722 is coupled operatively with arotating handle 750 to enable concomitant rotation therewith. Rotatinghandle 750 may be rotated to facilitate alignment of hook portion 722with connecting rod 10, as well as facilitating disengagement of rod 10from connecting rod slot 70. In this manner, the clinician may performthe unseating of connecting rod 10 from within connecting rod slot 70 ofinner housing 64 of bone screw 50 through pulling of a handle member 707when connecting rod 10 is engaged with hook portion 722, as well asrotating rotating handle 750.

With reference to FIGS. 22-24, spinal stabilization system 100 mayfurther include right and left in situ rod benders 800, 820, right andleft coronal rod benders 900, 920 and a tabletop rod bender 1200. Rightand left in situ rod benders 800, 820 each define a slot 802, 822,respectively, for selective reception of connecting rod 10 therein. Inparticular, each slot 802, 822 has a substantially rectangular wall 802a, 822 a configured to engage elongate head portion 14 of connecting rod10 in a single orientation. Right and left in situ rod benders 800, 820are configured for bending connecting rod 10 subsequent to placement ofconnecting rod 10 within the body. Right and left coronal rod benders900, 920 also each define a slot 902, 922, respectively, for selectivereception of connecting rod 10 therein. Each slot 902, 922 includes anarcuate end wall 902 a, 922 a configured to engage elongate roundedsection 12 of connecting rod 10 in a single orientation. Right and leftcoronal rod benders 900, 920 are configured for bending connecting rod10 prior to placement of connecting rod 10 within the body. Table topbender 1200 includes a jaw mechanism 1220 configured and adapted forbending connecting rod 10. Table top bender 1200 includes an alternativejaw mechanism (not shown) configured for cutting connecting rod 10.

With reference to FIGS. 25-31, spinal stabilization system 100 mayfurther include a cross connector assembly 1000 configured to coupleconnecting rods 10 to each other. Cross connector assembly 1000 includesa pair of connectors 1020 and an intermediate portion 1050 connectingthe pair of connectors 1020. Each connector 1020 defines a recessedportion 1022 configured to be fixed securely to connecting rod 10. Inparticular, each connector 1020 defines a slit 1024 configured to flexor enlarge the dimensions of recessed portion 1022 to facilitateinsertion of connecting rod 10. Recessed portion 1022 includes asubstantially rectangular wall 1022 a configured to engage elongate headportion 14 of connecting rod 10 and an opposing arcuate wall 1022 bconfigured to engage elongate rounded section 12 of connecting rod 10.In particular, recessed portion 1022 includes fingers 1022 c to secureconnecting rod 10 within recess portion 1022.

In addition, each connector 1020 defines a bore 1026 (FIG. 29) and asocket 1028 (FIG. 29). Bore 1026 is configured and dimensioned toreceive a screw 1044. Socket 1028 is configured and dimensioned toreceive a ball joint 1052, 1054 of intermediate portion 1050. Eachconnector 1020 further defines a slit 1032 configured to flex or enlargesocket 1028 to facilitate insertion of ball joint 1052, 1054 ofintermediate portion 1050 therein.

Upon insertion of connecting rod 10 in recessed portion 1022 and balljoint 1052, 1054 in socket 1028, screws 1044 are inserted into arespective bore 1026 to fix connecting rod 10 and ball joint 1052 inrecessed portion 1022 and socket 1028, respectively.

With particular reference now to FIG. 29, intermediate portion 1050includes an insertion arm 1060 and a receiving arm 1070. Receiving arm1070 defines a recessed portion 1072 configured and dimensioned toreceive slidably insertion arm 1060 therein. Insertion arm 1060 definesa bore 1066 configured to receive a set screw 1033 to fix a relativeposition of arms 1060, 1070. In this manner, the length of intermediateportion 1060 may be adjustable by the clinician. Insertion arm 1060 andreceiving arm 1070 include ball joint 1054, 1052 configured to bereceived in socket 1028. Under such a configuration, ball joints 1052,1554 enable variable or polyaxial adjustment between connector 1020 andintermediate portion 1050 prior to fastening of screw 1044. As such, thelength and orientation of intermediate portion 1050 relative toconnector 1020 may be selectively chosen by the clinician prior tofastening set screw 1033 and screws 1044.

With reference to FIG. 32, spinal stabilization system 100 may furtherinclude a cross connector assembly 2000 configured to couple variousconnecting rods 10, 11 to each other. For example, connecting rod 11 isa 5.5 mm diameter round rod. Connecting rod 10, as describedhereinabove, includes elongate rounded section 12 having a substantiallycircular cross-section, an elongate head portion 14, and a neck portion16 that connects and transitions elongate rounded section 12 intoelongate head portion 14, and thereby providing reduced stressconcentration along the elongate body of connecting rod 10.

Cross connector assembly 2000 includes connectors 2020, 2030. Connector2020 defines a recessed portion 2022 configured to receive connectingrod 11 therein. Similar to connector 1020, connector 2020 defines a slit2024 configured to flex or enlarge the dimensions of recessed portion2022 to facilitate insertion of connecting rod 11. Recessed portion 2022includes a pair of opposing fingers 2022 a (only one shown) to secureconnecting rod 10 within recess portion 2022. In addition, connector2020 defines a bore 2026 and a socket 2028. Bore 2026 is configured anddimensioned to receive a screw 1044. Socket 2028 is configured anddimensioned to receive a ball joint 2052 of connector 2030. Connector2020 further defines a slit 2032 configured to flex or enlarge socket2028 to facilitate insertion of ball joint 2052 of connector 2030.

Connector 2030 includes an elongate body 2035 having ball joint 2052configured and dimensioned to be received in socket 2028 and a graspingportion 2070. In particular, grasping portion 2070 defines a recess 2071configured and dimensioned to receive at least a portion of elongatehead portion 14 of connecting rod 10. Recess 2071 has a substantiallyrectangular shape configured to engage elongate head portion 14 ofconnecting rod 10. Moreover, recess 2071 defines a pair of opposingfingers 2071 a that secures elongate head portion 14 within recess 2071.In order to secure elongate head portion 14 between opposing fingers2071 a, connector 2030 may be made of a material that provides suitableflexibility to provide a snap-fit engagement with elongate head portion14. Alternatively, connector 2030 may be made of a rigid material inwhich case, one end of elongate head portion 14 may slide into recess2071.

In addition, connector 2030 further defines a bore 2075 configured anddimensioned to receive screw 1044 to fix connecting rod 10 to connector2030. Upon insertion of connecting rod 11 in recessed portion 2022 andball joint 2052 of connector 2030 in socket 2028 of connector 2020,screw 1044 is inserted into bore 2026 to fix connecting rod 11 inrecessed portion 2022 and ball joint 2052 in socket 2028. Similarly,screw 1044 is used to secure connecting rod 10 with connector 2030. Inthis manner, cross connector assembly 2000 enables coupling of variousconnecting rods with various cross-sections and diameters.

With reference now to FIG. 33, spinal stabilization system 100 mayfurther include a cross connector assembly 3000 configured to coupleconnecting rods 10 to each other. Cross connector assembly 3000 includesan elongate body 3035 having a grasping portion 3070 at one end ofelongate body 3035 and a grasping portion 3090 at another end ofelongate body 3035. The structure and method of using grasping portions3070, 3090 are substantially identical to grasping portion 2070, asdescribed hereinabove, and thus will not be described herein.

With reference now to FIGS. 34 and 34A, spinal stabilization system 100may further include an axial connector 4000. Axial connector 4000 isconfigured to connect connecting rods 10, 11 in a substantially linearfashion. However, the type of rods axial connector 4000 may connect arenot limited to connecting rods 10, 11. Axial connector 4000 may be usedto extend a rod construct that exists on the same side of the spinousprocess or to change rod diameter or type along the construct. Due tothe deformity being corrected, it is sometimes beneficial to havedifferent rod types to allow for a change in the type of correctionneeded. The axial connector 4000 is locked to the connecting rods 10, 11with screws 1044.

With continued reference to FIGS. 34 and 34A, axial connector 4000includes an elongate body 4100 defining a longitudinal bore 4102. Thecross-section of longitudinal bore 4102 generally corresponds to thecross-section of connecting rod 10. In this manner, both connecting rods10, 11 can be received through longitudinal bore 4102. Moreover,elongate body 4100 further defines a plurality of bores 4045 configuredand dimensioned to receive screws 1044 therein to fix connecting rods10, 11 to axial connector 4000. As described above, it is contemplatedthat various connecting rods may be used with axial connector 4000. Forexample, two connecting rods 10 may be used for a suitable construct, asshown in FIG. 35.

With reference now to FIGS. 36 and 36A, spinal stabilization system 100may further include an offset connector 5000 to connect, for example,connecting rods 10, 11. Offset connector 5000 may typically be used toextend a rod construct that exists on the same side of the spinuousprocess or to change rod diameter or type along the construct. Due tothe deformity being corrected, it is sometimes beneficial to havedifferent rod types to allow for a change in the type of correctionneeded. Offset connector 5000 is locked to connecting rods 10, 11 withset screws.

With continued reference to FIGS. 36 and 36A, offset connector 5000includes a body 5100. Body 5100 includes a first connecting portion 5200and a second connecting portion 5300 disposed adjacent first connectingportion 5200. First connecting portion 5200 defines a bore 5250configured and dimensioned to receive connecting rod 10 therethrough.First connecting portion 5200 further defines a hole 5109 to threadablyreceive screw 1044 to fix connecting rod 10 with first connectingportion 5200. Second connecting portion 5300 defines a recess 5350configured and dimensioned to receive connecting rod 11. Recess 5350 maydefine an arcuate portion 5351 to accommodate connecting rods withcircular cross-section. Preferably, recess 5350 has a depth greater thanthe diameter of connecting rod 11, such that various diameter connectingrods may be accommodated in recess 5350. The varying diameter of variousconnecting rods will be fixed securely in second connecting portion 5300by screw 1044. In addition, offset connector 5000 is not limited to thecombination of connecting rods 10, 11. For example, a pair of connectingrods 10 may be used with offset connector 5000, as shown in FIGS. 37 and37A.

With reference now to FIGS. 38 and 38A, spinal stabilization system 100may further include a spinal hook 6000. Spinal hook 6000 may be used toconnect the connecting rod to the anatomy in various locations. Somespinal hooks 6000 are used with the lamina, others with the pedicle.Spinal hook 6000 can also have a variety of sizes, shapes and angles toaccommodate the anatomy. The spinal hook 6000 may be locked toconnecting rod 10 with screw 1044. Spinal hook 6000 includes a body 6100and a hook 6150 extending therefrom. Body 6150 defines a recess 6200configured and dimensioned to receive connecting rod 10 therein. Thecross-section of recess 6200 generally corresponds to the cross-sectionof connecting rod 10, which also accommodates round connecting rod 11.As described above, it is contemplated that various connecting rods maybe used with spinal hook 6000. Screw 1044 is used to fix connecting rod10 to spinal hook 6000.

In use, two or more bone screws 50 are affixed to two or more vertebralbodies. Connecting rod 10 is then bent using one or more of the rodbenders 80, 800, 820, 900, 920, 1200 to conform connecting rod 10 to theconfiguration necessary to achieve proper alignment of the vertebralbodies. Once connecting rod 10 is appropriately bent, a clinician placesconnecting rod 10, by hand, in alignment with dual layered housing 60 ofbone screws 50 such that elongate rounded portion 12 is received withinconnecting rod slot 70 of dual layered housing 60 of bone screw 50. Onceconnecting rod 10 is properly aligned with dual layered housing 60 ofbone screw 50, reduction device 200 is attached to dual layered housing60 to seat connecting rod 10 within connecting rod slot 70 of bone screw50. Partial locker 300 is then placed over reduction device 200 andengaged with dual layered housing 60 of bone screw 50 to partially lockconnecting rod 10 to dual layered housing 60. Partial locker 300 and oneor more reduction devices 200 are then disengaged from dual layeredhousing 60. At this point, connecting rod 10 may be rotationallyadjusted relative to dual layered housing 60 of bone screw 50. In situbenders 800, 820 may also be used to further bend connecting rod 10.Upon proper orientation of connecting rod 10, quick locker 500 isengaged with dual layered housing 60 of bone screw 50 to fully lockconnecting rod 10 within dual layered housing 60 of bone screw 50.

In the case of using more than one connecting rod 10, 11, crossconnectors 1000, 2000, 3000, axial connector 4000, and/or offsetconnector 5000 may be utilized to further secure connecting rods 10, 11to vertebrae. Initially, a bone screw 50 is inserted into a pedicle andanother is inserted into a pedicle of the same vertebral level on theopposite side of the spinous process. Two additional bone screws 50 areinserted into pedicles at a position cranial (or distal) to the firsttwo screws 50 at the same vertebral level. A connecting rod 10, 11 isinserted into two bone screws on one side of the spinous process andanother connecting rod (of the same or different cross section ordiameter) 10, 11 is inserted into the two bone screws 50 on the oppositeside of the spinous process. Bone screws 50 are locked and then asuitable cross connector 100, 2000, 3000 is attached to the twoconnecting rods 10, 11 and locked into place. Spinal hook 6000 may beused as needed to provide additional stabilization.

Another method involves the construct above and in addition, theplacement of axial connector 4000 at the distal end of both connectingrods 10, 11. Subsequent to the placement of axial connector 4000, twomore bone screws 50 are inserted into opposing pedicles at the same ordifferent vertebral level. A connecting rod 10, 11 (of the same ordifferent diameter or cross section) is inserted into bone screws 50 andinto axial connectors 4000. Bone screws 50 are locked to connecting rods10, 11 and axial connectors 4000 are locked to connecting rods 10, 11 tocomplete the construct. Alternatively, offset connector 5000 may beused.

With reference to FIGS. 39 and 40, another embodiment of the presentdisclosure is shown generally as a spinal stabilization system 1000.Spinal stabilization system 1000 includes at least one bone screw 50 anda connecting rod 500 releasably secured to bone screw 50. Connecting rod500 is configured and dimensioned to be selectively and releasablysecured to bone screw 50. Connecting rod 500 is defined by an elongatebody of a particular length. The elongate body is made of abiocompatible material such as Titanium (Ti-CP) and its alloys (e.g.,Ti-6A1-4V), Cobalt-Chrome Alloy (CoCr) or Stainless Steel (SS).

With particular reference to FIG. 39, the elongate body of connectingrod 500 includes a first portion 510, a second portion 570, and atransition portion 550 that connects or transitions first portion 510 tosecond portion 570. First portion 550 is substantially identical toconnecting rod 10. First portion 550 includes an elongate roundedsection 512 having a substantially circular cross-section, an elongatehead portion 514, and a neck portion 516 that connects and transitionselongate rounded section 512 into elongate head portion 514, and therebyproviding reduced stress concentration along the elongate body of firstportion 510.

Elongate rounded section 512 of first portion 510 is configured anddimensioned to be received in connecting rod slot 70 of inner housing64. For example, rounded section 512 of first portion 510 may have astandard diameter of, for example, about 5.5 mm, suitable to mate withconnecting rod slot 70.

Elongate head portion 514 has a substantially rectangular cross-sectionhaving suitable dimensions of, for example, about 6 mm×about 1 mm (0.246in.×0.039 in.). However, it is envisioned that elongate head portion 514may have a cross-section that is substantially square, elliptical or anyother shape to add rigidity to rounded section 512 of first portion 510.

Neck portion 516 has dimensions that are smaller than those of elongaterounded section 512 and elongate head portion 514. Neck portion 516defines a pair of concave sides joining elongate head portion 514 toelongate rounded section 512, so that the concave sides provideclearance for the taper lock screw housings.

Bone screw 50 may be positioned at any desired position along theelongate body of connecting rod 500. When first portion 510 is securedto bone screw 50, neck portion 516 of first portion 510 is disposed atthe top of bone screw 50 and does not interfere with the interactionbetween first portion 510 and bone screw 50. Furthermore, elongate headportion 514 of first portion 510 is disposed above the top of taper lockscrew 50.

With continued reference to FIG. 39, transition portion 550 transitionsfirst portion 510 to second portion 570. Transition portion 550 isconfigured to reduced stress concentration along the elongate body ofconnecting rod 500. In particular, transition portion 550 includes anelongate head portion 554, an elongate rounded section 552 that issubstantially identical to elongate rounded section 512 of first portion510, and a neck portion 556 that connects and transitions elongaterounded section 552 into elongate head portion 554. In particular,transition portion 550 is longitudinally tapered such that an endportion thereof adjacent first portion 510 has a cross section that issubstantially identical to a cross section of first portion 510 and anopposite end portion thereof adjacent second portion 570 has a crosssection that is substantially identical to a cross section of secondportion 570. Second portion 570 includes a circular rod 600concentrically aligned and coupled to elongate rounded section 552 oftransition portion 550. Circular rod 600 is configured and dimensionedto be received in connecting rod slot 70 of bone screw 50.

First portion 510 provides a greater stiffness and rigidity thancircular rod 600 of second portion 570. Under such a configuration, asingle body connecting rod 500 provides a non-uniform stiffness andrigidity. In addition, first and second portions 510, 570 do not requireany design changes to taper lock screw 50, and thus advantageouslyprovide efficiency of manufacture and inventory. The elongate body ofconnecting rod 500 may be monolithically formed as a unitary construct.For example, connecting rod 500 may be machined from a single piece ofbar stock.

Although the illustrative embodiments of the present disclosure havebeen described herein with reference to the accompanying drawings, theabove description, disclosure, and figures should not be construed aslimiting, but merely as exemplifications of particular embodiments. Forexample, it is contemplated that elongate head portion 14 of connectingrod 10 need not extend over substantially the entire the elongate bodyof connecting rod 10, but instead may only be provided in a portion ofconnecting rod 10 where it is desired to enhance the rigidity of thatportion of the rod. One skilled in the art will recognize that thepresent disclosure is not limited to use in spine surgery, and that theinstrument and methods can be adapted for use with any suitable surgicaldevice. It is to be understood, therefore, that the disclosure is notlimited to those precise embodiments, and that various other changes andmodifications may be effected therein by one skilled in the art withoutdeparting from the scope or spirit of the disclosure.

1. A spinal stabilization system comprising: a connecting rod includingan elongate round portion, an elongate head portion and a neck portionconnecting the elongate round portion with the elongate head portion;and a bone screw including a housing portion and a screw shaft extendingdistally from the housing portion, the housing portion including aninner housing and an outer housing slidably surrounding at least aportion of the inner housing, the inner housing defining a slotconfigured and dimensioned to releasably secure the elongate roundportion of the connecting rod therein, wherein the outer housing ismovable relative to the inner housing between an unlocked state in whichthe elongate round portion of the connecting rod is releasable from theslot defined in the inner housing and a locked state in which theconnecting rod is secured to the slot.
 2. The spinal stabilizationsystem according to claim 1, wherein the elongate head portion of theconnecting rod has a non-circular cross-section.
 3. The spinalstabilization system according to either claim 1, wherein the elongatehead portion of the connecting rod has a substantially rectangularcross-section.
 4. The spinal stabilization system according to claim 1,wherein the neck portion of the connecting rod has an arcuate profile.5. The spinal stabilization system according to claim 4, wherein theneck portion is narrower than the elongate round portion.
 6. The spinalstabilization system according to claim 1, wherein the neck portion andthe elongate head portion of the connecting rod are disposed proximal ofthe inner housing when the elongate round portion of the connecting rodis disposed in the slot defined in the inner housing.
 7. The spinalstabilization system according to claim 1, wherein the connecting rod ismonolithically formed.
 8. The spinal stabilization system according toclaim 1, wherein the screw shaft is polyaxially coupled to the housingportion.
 9. The spinal stabilization system according to claim 1,wherein the outer housing includes a circumferentially disposed flange.10. The spinal stabilization system of claim 1, further comprising aplurality of bone screws.
 11. A spinal stabilization system comprising:a connecting rod including an elongate round portion, an elongate headportion and a neck portion connecting the elongate round portion withthe elongate head portion; at least one rod bending device including anelongate body defining an aperture configured and dimensioned to receivetherethrough the connecting rod in a single orientation; and a bonescrew including a housing portion and a screw shaft rotatably extendingdistally from the housing portion, the housing portion including aninner housing and an outer housing slidably surrounding at least aportion of the inner housing, the inner housing defining a slotconfigured and dimensioned to releasably secure the elongate roundportion of the connecting rod therein, wherein the outer housing ismovable relative to the inner housing between an unlocked state in whichthe elongate round portion of the connecting rod is releasable from theslot defined in the inner housing and a locked state in which theconnecting rod is secured to the slot.
 12. The spinal stabilizationsystem according to claim 11, wherein the at least one rod bendingdevice further includes a second aperture oriented orthogonal to theaperture.
 13. The spinal stabilization system according to claim 11,wherein side walls defining the aperture have an arcuate profile. 14.The spinal stabilization system according to claim 11, wherein theaperture includes a round portion and a non-circular portion.
 15. Thespinal stabilization system according to claim 14, wherein thenon-circular portion of the aperture has a substantially rectangularshape.
 16. A method of stabilizing a spine, the method comprising:providing a spinal stabilization system including: a connecting rodincluding an elongate round portion, an elongate head portion and a neckportion connecting the elongate round portion with the elongate headportion; a pair of rod bending devices each including an elongate bodydefining an aperture configured and dimensioned to receive therethroughthe connecting rod in a single orientation; and a bone screw including ahousing portion and a screw shaft extending distally from the housingportion, the housing portion including an inner housing and an outerhousing slidably surrounding at least a portion of the inner housing,the inner housing defining a slot configured and dimensioned toreleasably secure the elongate round portion of the connecting rodtherein, wherein the outer housing is movable relative to the innerhousing between an unlocked state in which the elongate round portion ofthe connecting rod is releasable from the slot defined in the innerhousing and a locked state in which the connecting rod is secured to theslot; implanting a plurality of bone screws into a plurality ofvertebral bodies; bending the connecting rod using the rod bendingdevices; inserting the elongated round portion of the connecting rodinto the connecting rod slots in the plurality of bone screws with thehead portion disposed above the screws; and locking the connecting rodin the connecting rod slots in the plurality of bone screws.
 17. Themethod according to claim 16, wherein the elongate head portion of theconnecting rod has a non-circular cross-section.
 18. The methodaccording to either claim 16, wherein the elongate head portion of theconnecting rod has a substantially rectangular cross-section.
 19. Themethod according to claim 16, wherein bending the connecting rodincludes inserting the connecting rod through the apertures of the pairof rod bending devices and applying force to the connecting rod throughthe handle members of the rod bending devices.
 20. The method accordingto claim 19, wherein bending the connecting rod includes bending theconnecting rod in an anterior-posterior orientation.
 21. The methodaccording to claim 19, wherein bending the connecting rod includesbending the connecting rod in a medial-lateral orientation.
 22. Themethod according to claim 16, wherein the pair of rod bending deviceseach includes a plurality of apertures configured and dimensioned toreceive therethrough the connecting rod, the plurality of aperturesdefined in different orientations.
 23. The method according to claim 22,wherein bending the connecting rod includes inserting the connecting rodthrough the apertures of the pair of rod bending devices havingdifferent orientations and applying twisting force.
 24. The methodaccording to claim 16, wherein inserting the connecting rod into theconnecting rod slots in the bone screws includes positioning theelongate round portion of the connecting rod in the connecting rod slotsin the plurality of bone screws.
 25. The method according to eitherclaim 16, wherein bending the connecting rod includes bending theconnecting rod to conform to a desire contour of the spine.
 26. Themethod according to claim 16, wherein the housing portion of the bonescrew is rotatably coupled with the screw shaft.
 27. The methodaccording to either claim 16, further comprising orienting the pluralityof bone screws to the contour of the connecting rod prior to locking theconnecting rod in the connecting rod slots in the plurality of bonescrews.
 28. The method according to either claim 16, wherein locking theconnecting rod in the connecting rod slots in the plurality of bonescrews includes partially locking the connecting rod in the connectingrod slots.
 29. A connecting rod bending device comprising: a handlemember; and an elongate body extending from the handle member, theelongate body defining a non-circular aperture configured anddimensioned to receive a non-circular rod in a particular orientation.30. The connecting rod bending device according to claim 27, wherein theelongate body further defines a plurality of non-circular apertures, theplurality of non-circular apertures being defined in variousorientations, whereby a connecting rod can be received in variety oforientations with respect to the elongate body.
 31. The connecting rodbending device according to claim 28, wherein the plurality ofnon-circular apertures are orthogonal to each other.
 32. The connectingrod bending device according to claim 27, wherein the non-circularaperture includes an arcuate portion and a substantially rectangularportion.
 33. A kit for spinal surgery comprising: a connecting rodincluding an elongate round portion, an elongate head portion and a neckportion connecting the elongate round portion with the elongate headportion; a bone screw including a housing portion and a screw shaftextending distally from the housing portion, the housing portionincluding an inner housing and an outer housing slidably surrounding atleast a portion of the inner housing, the inner housing defining a slotconfigured and dimensioned to releasably secure the elongate roundportion of the connecting rod therein, wherein the outer housing ismovable relative to the inner housing between an unlocked state in whichthe elongate round portion of the connecting rod is releasable from theslot defined in the inner housing and a locked state in which theconnecting rod is secured to the slot; a rod reduction device configuredand adapted for attachment to the housing portion of the bone screw toreduce the connecting rod into the slot defined in the inner housing; apartial locker configured to move the outer housing relative to theinner housing to partially lock the connecting rod to the dual layeredhousing; and a quick locker configured to move the outer housing withrespect to the connecting rod to fully lock the connecting rod to thedual layered housing.
 34. The kit according to claim 33, wherein thepartial locker includes a distal end portion configured and adapted toreceive the reduction device while the reduction device remains operablyengaged with the bone screw.
 35. The kit according to claim 33, furthercomprising an unlocker configured and adapted to move the outer housingof the bone screw relative to the inner housing and the connecting rodto fully unlock the connecting rod from the dual layered housing
 36. Thekit according to claim 33, further comprising a rod puller configuredand adapted to selectively engage the connecting rod to enable theunseating of the connecting rod from within the slot of the innerhousing of the bone screw.
 37. The kit according to claim 33, furthercomprising at least one rod bending device including an elongate bodydefining an aperture configured and dimensioned to receive therethroughthe connecting rod in a single orientation.
 38. The kit according toclaim 36, wherein the at least one rod bending device further includes asecond aperture oriented orthogonal to the aperture.
 39. A method ofstabilizing a spine, the method comprising: providing a spinalstabilization system including: a connecting rod including an elongateround portion, an elongate head portion and a neck portion connectingthe elongate round portion with the elongate head portion; a bone screwincluding a housing portion and a screw shaft extending distally fromthe housing portion, the housing portion including an inner housing andan outer housing slidably surrounding at least a portion of the innerhousing, the inner housing defining a slot configured and dimensioned toreleasably secure the elongate round portion of the connecting rodtherein, the outer housing being movable relative to the inner housingbetween an unlocked state in which the elongate round portion of theconnecting rod is releasable from the slot defined in the inner housingand a locked state in which the connecting rod is secured to the slot; arod reduction device configured and adapted for attachment to thehousing portion of the bone screw to reduce the connecting rod into theslot defined in the inner housing; a partial locker configured to movethe outer housing relative to the inner housing to partially lock theconnecting rod to the dual layered housing; and a quick lockerconfigured to move the outer housing with respect to the connecting rodto fully lock the connecting rod to the dual layered housing; implantinga plurality of bone screws into a plurality of vertebral bodies;inserting the elongated round portion of the connecting rod into theslots in the plurality of bone screws with the rod reduction device; andlocking the connecting rod in the slots in the plurality of bone screws.40. The method according to claim 39, wherein the spinal stabilizationsystem further includes a pair of rod bending devices each including anelongate body defining an aperture configured and dimensioned to receivetherethrough the connecting rod in a single orientation.
 41. The methodaccording to claim 40, further comprising bending the connecting rodusing the rod bending devices.
 42. The method according to claim 41,wherein bending the connecting rod includes inserting the connecting rodthrough the apertures of the pair of rod bending devices and applyingforce to the connecting rod through the elongate body of the rod bendingdevices.
 43. The method according to claim 39, further comprisingorienting the plurality of bone screws to the contour of the connectingrod prior to locking the connecting rod in the slots in the plurality ofbone screws.
 44. The method according to claim 39, wherein locking theconnecting rod in the slots in the plurality of bone screws includespartially locking the connecting rod in the slots with the partiallocker.
 45. The method according to claim 39, wherein locking theconnecting rod in the slots in the plurality of bone screws includesfully locking the connecting rod in the slots with the quick locker. 46.A connecting rod for use in a spinal stabilization surgery, theconnecting rod comprising: an elongate rounded portion; an elongate headportion having a non-circular cross-section; and a neck portionconnecting the elongate rounded portion with the elongate head portion,the neck portion having concave sides, wherein the neck portion hassmaller dimensions than those of the elongate rounded portion and theelongate head portion.
 47. The spinal stabilization system according toeither claim 46, wherein the elongate head portion of the connecting rodhas a substantially rectangular cross-section.
 48. The spinalstabilization system according to claim 46, wherein the connecting rodis monolithically formed.
 49. A spinal stabilization system comprising:a pair of connecting rods each including an elongate rounded portion, anelongate head portion, and a neck portion connecting the elongaterounded portion with the elongate head portion; and a cross connectorassembly configured to couple the pair of connecting rods, the crossconnector assembly including: a pair of connectors each defining arecessed portion configured to secure one of the pair of connecting rodstherein; and an intermediate portion connecting the pair of connectors,wherein the recessed portion includes an arcuate wall configured toreceive the elongate rounded portion of the connecting rod and anopposing non-circular wall configured to receive the elongate headportion of the connecting rod.
 50. The spinal stabilization systemaccording to claim 49, wherein each connector defines a slit configuredto flex or enlarge the dimensions of the recessed portion to facilitateinsertion of the connecting rod.
 51. The spinal stabilization systemaccording to claim 49, wherein the non-circular wall has a substantiallyrectangular cross-section.
 52. The spinal stabilization system accordingto claim 49, wherein the recessed portion includes a pair of opposingfingers to secure the connecting rod within the recessed portion. 53.The spinal stabilization system according to claim 49, wherein theintermediate portion is retractable to enable adjustment of a length ofthe intermediate portion.
 54. The spinal stabilization system accordingto claim 49, further comprising a circular rod, wherein the arcuate wallof the recessed portion is configured to receive the circular rodtherein.
 55. A spinal stabilization system comprising: a pair ofconnecting rods each including an elongate rounded portion, an elongatehead portion, and a neck portion connecting the elongate rounded portionwith the elongate head portion; and a cross connector assemblyconfigured to couple the pair of connecting rods, the cross connectorincluding a pair of connectors each defining a recessed portionconfigured to secure one of the pair of connecting rods therein, therecessed portion is configured to receive the elongate head portion ofthe connecting rod, each recessed portion defining a pair of fingers tosecure the elongate head portion therebetween.
 56. The spinalstabilization system according to claim 55, wherein the cross connectoris made of a relatively flexible material to provide a snap fitengagement with the elongate head portion.
 57. A spinal stabilizationsystem comprising: a connecting rod including a first portion and asecond portion, the first portion including an elongate round portion,an elongate head portion, and a neck portion connecting the elongateround portion with the elongate head portion, the second portionincluding a circular rod, the circular rod coupled to the elongate roundportion; and a bone screw including a housing portion and a screw shaftextending distally from the housing portion, the housing portionincluding an inner housing and an outer housing slidably surrounding atleast a portion of the inner housing, the inner housing defining a slotconfigured and dimensioned to releasably secure the connecting rodtherein, wherein the outer housing is movable relative to the innerhousing between an unlocked state in which the connecting rod isreleasable from the slot defined in the inner housing and a locked statein which connecting rod is secured to the slot.
 58. The spinalstabilization system according to claim 57, wherein the connecting rodfurther includes a transition portion connecting the first and secondportions, the transition portion being longitudinally tapered.
 59. Thespinal stabilization system according to claim 58, wherein thetransition portion includes a first end having a cross sectionsubstantially identical to a cross section of the first portion and asecond end having a cross section substantially identical to the crosssection of the second portion.
 60. The spinal stabilization systemaccording to claim 59, wherein the first end is adjacent the firstportion and the second end is adjacent the second portion.
 61. Thespinal stabilization system according to claim 57, wherein theconnecting rod is monolithically formed.
 62. A connecting rod for usewith a bone screw comprising: an elongate round section configured to bereceived in a slot defined in a housing of the bone screw; an elongatehead portion; and a neck portion connecting the elongate round sectionto the elongate head portion, wherein the neck portion and the elongatehead portion are configured and dimensioned to be disposed proximal ofthe housing when the elongate round section is disposed in the slot. 63.The connecting rod according to claim 62, wherein the housing includesan inner housing and an outer housing selectively positionable relativeto the inner housing to lock the connecting rod in position within theslot defined by the inner housing.
 64. The connecting rod according toclaim 63, wherein the outer housing is transitionable relative to theinner housing between a locked position in which the connecting rod isfully locked in position within the inner housing and an unlockedposition in which the connecting rod is movable within the innerhousing, wherein the neck portion is configured to provide a space topermit transition of the outer housing between the locked and unlockedpositions.
 65. The connecting rod according to claim 63, wherein theneck portion is spaced apart from the inner housing when the elongateround section is disposed in the slot.
 66. The connecting rod accordingto claim 62, wherein the elongate head portion has a non-circularcross-section.
 67. The connecting rod according to claim 62, wherein theneck portion of the connecting rod has an arcuate profile.
 68. Theconnecting rod according to claim 62, wherein the neck portion defines apair of concave sides joining the elongate head portion to the elongateround section.
 69. The connecting rod according to claim 62, wherein theelongate round section has a generally circular cross-section.
 70. Theconnecting rod according to claim 62, wherein the neck portion isnarrower than the elongate round section.
 71. The connecting rodaccording to claim 62, wherein the elongate head portion, the elongateround section, and the neck portion are monolithically formed.
 72. Theconnecting rod according to claim 62, wherein at least one of theelongate round section, the elongate head portion, and the neck portionis formed from a biocompatible material.
 73. The connecting rodaccording to claim 62, wherein at least one of the elongate roundsection, the elongate head portion, and the neck portion is formed froma material selected from a group consisting of titanium, titanium alloy,cobalt-chrome alloy, and stainless steel.
 74. The connecting rodaccording to claim 62, wherein the elongate head portion has asubstantially rectangular cross-section.